Synergistic effect enhancing the energy transfer efficiency of carbon dots-based molecular beacon probe for ultrasensitive detection of microRNA

Abstract

An ultrasensitive molecular beacon (MB) probe employing carbon dots (CDs) as energy donor and organic dye and graphene oxide (GO) as synergistic quencher was constructed for microRNA-21 (miRNA-21) determination. The MB probe (CDs-MB-BHQ1) was first fabricated by conjugating CDs on the 5′ end of BHQ1-tagged MB, and the fluorescence of CDs decreased owing to the occurrence of luminescence resonance energy transfer (LRET). GO was introduced as a synergistic quencher, thus effectively enhancing the energy transfer efficiency through the interaction between GO and the loop region of MB. In the presence of miRNA-21, it hybridized with loop of MB, thus bringing CDs-MB-BHQ1 away from the surface of GO and increasing the distance between CDs and BHQ1. Owing to the inhibition of LRET process, the fluorescence of CDs at 513 nm (excitation at 490 nm) was recovered. This probe exhibited excellent specificity and could be applied to miRNA-21 determination (0.5–800 pM). Moreover, this proposed probe could monitor the content of miRNA-21 in real human serums, and accuracy were verified by qRT-PCR method (Er ≤ 15.3%) and recovery experiments (recoveries ranged from 88.0% to 105%).